This paper investigates the generation of complex bursting patterns in Van der Pol system with two slowly changing external forcings. Complex bursting patterns, including complex periodic bursting and chaotic bursting...This paper investigates the generation of complex bursting patterns in Van der Pol system with two slowly changing external forcings. Complex bursting patterns, including complex periodic bursting and chaotic bursting, are presented for the cases when the two frequencies are commensurate and incommensurate. These complex bursting patterns are novel and have not been reported in previous work. Based on the fast-slow dynamics, the evolution processes of the slow forcing are presented to reveal the dynamical mechanisms undedying the appearance of these complex bursting patterns. With the change of ampli- tudes and frequencies, the slow forcing may visit the spiking and rest areas in different ways, which leads to the generation of different complex bursting patterns.展开更多
To analyze the mechanism of drag reducing effect by coupling flexible tubes with turbulent flow, based on experimental examination of more obvious turbulent drag reduction effect in flexible tubes than in rigid tubes,...To analyze the mechanism of drag reducing effect by coupling flexible tubes with turbulent flow, based on experimental examination of more obvious turbulent drag reduction effect in flexible tubes than in rigid tubes, experimental investigation was performed on the effect of turbulent drag reduction, fluctuating vibration characteristics of flexible tube and the correlations by using a double-tube system and laser displacement sensor. The results are as follows： with the decrease of the thickness of the flexible tubes, the root mean square of fluctuating amplitude of the outer wall of the tubes increases, and the non-dimensional burst period increases, resulting in the increase of the reduction rate of drag coefficient by coupling flexible tubes with turbulent flow. At applied pressure-balanced air on the outer wall and the Reynolds number of about 1.75×10^4, the non-dimensional burst periods of the flexible tubes with the thickness of 2 mm, 3 mm, 4 mm are 141, 126, 105, respectively.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10872080, 20976075, 10972091 and 11102076)the Research Foundation for Advanced Talents of Jiangsu University (Grant No. 11JDG075)the Natural Science Foundation of Higher Education Institutions of Jiangsu Province (Grant No. 10KJD110006)
文摘This paper investigates the generation of complex bursting patterns in Van der Pol system with two slowly changing external forcings. Complex bursting patterns, including complex periodic bursting and chaotic bursting, are presented for the cases when the two frequencies are commensurate and incommensurate. These complex bursting patterns are novel and have not been reported in previous work. Based on the fast-slow dynamics, the evolution processes of the slow forcing are presented to reveal the dynamical mechanisms undedying the appearance of these complex bursting patterns. With the change of ampli- tudes and frequencies, the slow forcing may visit the spiking and rest areas in different ways, which leads to the generation of different complex bursting patterns.
基金the National Natural Science Foundation of China(Grant No. 50504021)Hunan Provincal Educational Department (Grant No. 06C265)The Key Science and Technology Project of Ministry of Education of the PRC(Grant No. 206122).
文摘To analyze the mechanism of drag reducing effect by coupling flexible tubes with turbulent flow, based on experimental examination of more obvious turbulent drag reduction effect in flexible tubes than in rigid tubes, experimental investigation was performed on the effect of turbulent drag reduction, fluctuating vibration characteristics of flexible tube and the correlations by using a double-tube system and laser displacement sensor. The results are as follows： with the decrease of the thickness of the flexible tubes, the root mean square of fluctuating amplitude of the outer wall of the tubes increases, and the non-dimensional burst period increases, resulting in the increase of the reduction rate of drag coefficient by coupling flexible tubes with turbulent flow. At applied pressure-balanced air on the outer wall and the Reynolds number of about 1.75×10^4, the non-dimensional burst periods of the flexible tubes with the thickness of 2 mm, 3 mm, 4 mm are 141, 126, 105, respectively.
